The LCD (Liquid Crystal Display) possesses advantages of thin body, power saving and no radiation to be widely used in many application scope. It has been widely utilized in, such as mobile phones, PDAs (personal digital assistance), digital cameras, laptop screens or notebook screens. The present thin film transistor liquid crystal display comprises a shell, a LCD panel located in the shell and a backlight module located in the shell. Particularly, the structure of the LCD panel mainly comprises a TFT Array Substrate (Thin Film Transistor Array Substrate), a CF (Color Filter) and a Liquid Crystal Layer. The working principle is that the light of backlight module is reflected to generate images by applying driving voltages to the two glass substrate for controlling the rotations of the liquid crystal molecules.
Quantum dot is a semiconductor nano crystal, of which the radius is smaller then or close to Bohr radius and is three dimension nano material that most is composed by II-VI elements or III-V elements. Because of the quantum confinement effect, the transportation of the inner electrons and holes are restricted to make the continuous energy band structure become the disjunct level structure. When the dimensions of the quantum dots are different, the confinement degrees of the electrons and the holes are different and the disjunct level structures are different. After being excited by the external energy, the lights of various wavelengths, i.e. the light of kinds of colors, are emitted by the quantum dots of various dimensions. The advantages of the quantum dots are: by controlling the dimensions of the quantum dots, the achievable light emitting wavelength range can cover the infrared ray to the entire visible light band. The light emitting band is narrow, and the color saturation is high; the quantum conversion efficiency of the quantum dot material is high; the material property is stable; the manufacture method is simple but varied. It can be manufactured by solution and the resource is very much.
The liquid crystal display based on quantum dots is the most possible display device to achieve the practicability to provide significant function in the field of information communication and transmission. The fluorescence intensity and the stability of the quantum dot is very well and the quantum dot display will possess advantages of better image quality, lower power consumption, longer usage lifetime, and becomes one main direction of display technology development in the future. As being the light source of the backlight module in the liquid crystal display screen, the light excited by the blue light LED and the blue light are mixed to be white light having larger color gamut, and significantly promoting the image display quality.
FIG. 1 is a sectional structure diagram of a liquid crystal display according to prior art. It comprises a backlight module 100, and a liquid crystal panel 200 positioned on the backlight module 100; the liquid crystal panel 200 comprises a TFT substrate 210, a glass substrate 220 oppositely positioned to the TFT substrate 210, a color resist layer 230 positioned on the TFT substrate 210, a pixel electrode layer 240 positioned on the color resist layer 230, a liquid crystal layer 260 filled between the TFT substrate 210 and the glass substrate 220, alignment layers 270 respectively positioned at two side of the liquid crystal layer 260, a black matrix 280 positioned on the glass substrate 220, an upper polarizer 290 positioned on the upper surface of the glass substrate 220 and a lower polarizer 390 positioned at the lower surface of the TFT substrate 210, wherein the color resist layer 230 is a color resist layer doped with quantum dot material.
FIG. 2 is another sectional structure diagram of a liquid crystal display according to prior art. It comprises a backlight module 100, and a liquid crystal panel 200 positioned on the backlight module 100; the liquid crystal panel 200 comprises a TFT substrate 210, a glass substrate 220 oppositely positioned to the TFT substrate 210, a color resist layer 230 positioned on the glass substrate 220, a pixel electrode layer 240 positioned on the color resist layer 230, a liquid crystal layer 260 filled between the TFT substrate 210 and the glass substrate 220, alignment layers 270 respectively positioned at two side of the liquid crystal layer 260, a black matrix 280 positioned on the glass substrate 220, an upper polarizer 290 positioned on the upper surface of the glass substrate 220 and a lower polarizer 390 positioned at the lower surface of the TFT substrate 210, wherein the color resist layer 230 is a color resist layer doped with quantum dot material.
However, the liquid crystal display based on quantum dots must have some drawbacks as possessing many advantages. As shown in FIG. 1, after the light passes through the color resist layer 230 doped with quantum dot material, the outgoing direction is random. AS the scattering light through the color resist layer 230 passes through the liquid crystal layer 260, all lights of corresponding pixel dot positions cannot be well controlled anymore, and the liquid crystal display will occur the light leakage phenomenon. The working principle of the liquid crystal display is to utilize the optical rotation and the birefraction of the liquid crystal for controlling the rotation of the liquid crystal with the voltages and rotating the linearly polarized light passing through the upper polarizer thereby, and then raying the light from the lower polarizer (perpendicular to the upper polarizer). The polarizer and the cell function as being a light switch. Obviously, such light switch cannot function for the light emitted by the quantum dots at all.
Besides, the polarizer in the traditional liquid crystal display generally uses the iodine to be the dichrois substance. However, the sublimability of the iodine is high, and therefore the heat resistance and the light resistance are bad. The delustering color of the iodine is deep blue. Therefore, it is not an ideal colorless polarizer for the entire visible light range, and is bad for the display result of the liquid crystal display.